# Find the Phase: 1D

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Note that this exercise is intended to be solved by hand, without the use of computation.

The **signals** shown in the left column are periodic in n with period
N=20. The functions shown in the right column show the **angles** of Fourier
series.
For each signal, indicate which (if any) of the angle plots represents the
angles of that signal's Fourier series coefficients (where an "X" indicates an undefined phase).

Which angle plot matches with each signal? Enter a sequence of letters in the
box below. For example, entering `GDIC...`

would imply that angle graph `G`

matches with signal 1, angle graph `D`

matches with signal 2, `I`

with signal
3, `C`

with signal 4, ...

Matching letters: